In a manufacturing step of an electronic substrate such as a semiconductor manufacturing apparatus and a liquid crystal manufacturing apparatus, there is generated a residue of photoresist, a residue of an organic solvent, a synthetic wax, an organic residue of fatty acids and the like from a human body, an inorganic residue such as sodium, potassium, gold, iron and copper, as well as a contaminant such as fine particles, which must be removed so as not to be entrained to the subsequent steps. Accordingly, a cleaning and drying processing step, composed of chemicals processing using the chemicals or rinsing processing using rinsing liquid such as pure water, has become important, as technology for maintaining the substrate surface highly clean and efficiently removing the contaminants.
The apparatus described in PATENT LITERATURE 1 is a substrate cleaning apparatus for cleaning the substrate. The apparatus includes a means for rotating and holding substrate that holds and rotates the substrate, a means for supplying a cleaning liquid that supplies chemicals and rinsing liquid as a cleaning liquid to the substrate held by the means for rotating and holding substrate, and a member to contact with the cleaning liquid scattering from the substrate which is rotated by the means for rotating substrate. In PATENT LITERATURE 1, chemicals processing using the chemicals, and rinsing processing using pure water, etc. are performed to the substrate, while rotating the substrate holding parts and an atmosphere shielding plate.
In such an apparatus for performing the cleaning of the substrate, removal of contaminants adhered to the substrate is performed by supplying the chemicals like an acidic solution such as nitric acid aqueous solution, hydrochloric acid aqueous solution, hydrofluoric acid aqueous solution and mixed hydrofluoric acid aqueous solution (mixing of hydrogen peroxide water with hydrofluoric acid water) or an alkaline solution such as ammonia water and SC-1 (mixed solution of ammonia water and hydrogen peroxide water), or pure water toward the substrate held at the substrate holding unit, (hereinafter, an acidic solution or an alkaline solution is sometimes referred to as “chemicals”, in addition, pure water and chemicals are sometimes referred to as collectively “processing liquid”). Therefore, it has been known that the chemicals adheres to the substrate holding parts or an inert gas passage, and thus corrosion of the part adhered with the chemicals causes processing defect of the substrate.
Accordingly, it has been proposed to form a member of a processing apparatus to which the relevant chemicals adheres, using a resin having heat resistance and chemical resistance, to solve such processing defect of the substrate caused by such corrosion due to the chemicals, and as such a resin, there is included, for example, a fluoropolymer such as a tetrafluoroethylene resin (PTFE), a tetrafluoroethylene/fluoroalkoxytrifluoroethylene copolymer (PFA) (refer to PATENT LITERATURES 1 and 2). In particular, a bottle or a tube obtained by melt-extrusion molding of PFA, having a melt moldability, and being superior in heat resistance and chemical resistance, has been utilized as a container of a high purity chemicals for semiconductor manufacturing or a piping for transferring the chemicals or ultrapure water, respectively (refer to PATENT LITERATURE 3).
However, in recent years, as for a processing tank or the like in the substrate processing apparatus, where a plurality of processing liquids are supplied, there have been progressing the large sizing accompanying with a large-sized wafer, as well as shape complication or increase in parts number accompanying with multi-functionalization of washing or cleaning process, while high dimensional accuracy has been required.
To satisfy these requirements, the above processing tank or the like has been manufactured by cutting a large-size material of polytetrafluoroethylene (PTFE). However, such a method for obtaining a finished product of a processing tank has problems of low production efficiency, as well as an inevitable cutting waste of most part of the material, because it requires passing through long steps such as compression molding, sintering, cutting and annealing of a material block.
There has been attempted to obtain a material having a shape as near as possible to a final shape, using isostatic pressing or the like, to reduce cutting loss due to this cutting waste of PTFE, however, even by such a way, molding steps, which include compression molding, sintering, cutting and accompanying annealing and the like of a material block, require several months, and cutting loss (amount of cutting waste) also amounts over 50%.
In addition, in the case of attempting to obtain a large-sized processing tank, as described above, by injection molding, using PFA having chemical resistance and heat resistance equivalent to those of PTFE, and being heat meltable, for example, PFA having particular molecular weight distribution and melt flow rate (MFR) (35 to 60 g/10 minutes) at 372° C., measured in accordance with ASTM D-3307 as described in PATENT LITERATURE 4, or PFA having specific volume flow rate, as described in PATENT LITERATURE 5, it was difficult to obtain a large-size molded article by injection molding, because of not able to maintain enough injection pressure till the end of molding metal mold.
Obtaining the large-sized molded article of PFA by injection molding requires high injection pressure and clamping pressure, because PFA has higher melt viscosity as compared with other engineering plastics, therefore, there was a problem of requiring a very large-size injection molding machine. Accordingly, it has been impossible to obtain a large-size molded article of PFA by injection molding, because of hike of initial introduction cost and product cost, resulting in poor profitability, as well as difficulty in obtaining a practical large-size article.
In the case of obtaining a product, by subdividing parts of a large-sized tank or the like as described above to a size moldable by an existing PFA injection molding, molding the parts by an injection molding machine, and then by melt-adhering or welding them, there was a problem like generation of deformation by stress concentration at the melt-adhered or welded part, caused by thermal expansion in use of the product under high temperature atmosphere.
Still more, other melt molding methods, such as transfer molding, rotational molding and blow molding, have been attempted. However, for example, in the case of obtaining the above processing tank or the like by rotational molding, there were problems of poor cost reducing effect and low production efficiency, because of not satisfying high dimensional accuracy desired, resulting in many additional steps.